Re: Incorrect "variable might not have been initialized"

Lee Fesperman <>
Sat, 29 Apr 2006 23:09:19 GMT
Chris Uppal wrote:

Lee Fesperman wrote:

Sun's 1.4 javac gave me a "variable might not have been initialized"
error on the code below ... when it shouldn't have.

The compiler is correct. The JLS lays down very specific rules for when a
variable is deemed to be "definitely initialised", and your code doesn't
satisfy those conditions. See JLS Section 16.

I read JLS 16 several times. I'm obviously not a "language lawyer" because I could not
see why my code causes the error message. Would you care to explain further? Perhaps,
you could point to the relevant sub-section(s).

BTW, it works if I leave out the assignment to 'retain'.

I don't have 1.5 installed. Could someone try it on 1.5 for me?

I've just checked (JDK 1.5.0_06-b05), same thing happens.

If Test120 works on 1.5, try this one:

Also rejected.

Thanks ... also, to others who posted their results.

Lastly, this one works on 1.4 but not 1.2, so Sun seems to be making
progress in this area:

public class Test122
  public static void main(String[] args)
    boolean retain ;
    String ref ;
    if (retain = 1 > 0 && (ref = System.getProperty("user.home")) != null)
      System.out.println(ref) ;

After constant-folding "1 > 0", the compiler interprets that as:

    if (retain = ( (ref = System.getProperty("user.home")) != null ))

Yep, I shoulda realized that.

Lee Fesperman, FFE Software, Inc. (
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